CAPILLARY BONDING TOOL AND METHOD OF FORMING WIRE BONDS
A capillary bonding tool for wire bonding includes a first section, a second section and a bonding section. The first section has a first outer peripheral sidewall, an opposing first inner sidewall that extends generally parallel to the central longitudinal axis, and a first opening surrounded by the first inner sidewall. The second section has a second outer peripheral sidewall, an opposing second inner sidewall that extends at an angle with respect to the central longitudinal axis, and a second tapered opening surrounded by the second inner sidewall. The bonding section has a peripheral ridge extending axially outwardly from the second inner sidewall of the second section. The peripheral ridge has a third outer peripheral sidewall, a third inner tubular sidewall that extends generally parallel to the central longitudinal axis and radially outwardly of the first inner sidewall, and a third opening surrounded by the third inner tubular sidewall.
1 . A capillary bonding tool for making wire bonds, the capillary bonding tool comprising:
a central longitudinal axis;
a first section having a first outer peripheral sidewall, an opposing first inner sidewall which extends generally parallel to the central longitudinal axis, and a first opening surrounded by the first inner sidewall;
a second section having a second outer peripheral sidewall, an opposing second inner sidewall which extends at an angle with respect to the central longitudinal axis, and a second tapered opening surrounded by the second inner sidewall; and
a bonding section having a peripheral ridge extending axially outwardly from the second inner sidewall of the second section, the peripheral ridge having a third outer peripheral sidewall, a third inner tubular sidewall which extends generally parallel to the central longitudinal axis and radially outwardly of the first inner sidewall, and a third opening surrounded by the third inner tubular sidewall.
2 . The capillary bonding tool of claim 1 , wherein the second outer peripheral sidewall is positioned radially outwardly from the third outer peripheral sidewall and a generally horizontally extending ledge is positioned between the second outer peripheral sidewall and the third outer peripheral sidewall.
3 . The capillary bonding tool of claim 1 , wherein the second section has a first distal end surface extending from the second outer peripheral sidewall toward the second inner sidewall and the peripheral ridge has a second distal end surface extending from the third outer peripheral sidewall to the third inner sidewall, an outer diameter of the second distal end surface being smaller than an outer diameter of the first distal end surface.
4 . The capillary bonding tool of claim 3 , wherein the second distal end surface is a generally flat distal tip of the capillary bonding tool.
5 . The capillary bonding tool of claim 1 , wherein the second opening has a first end and a second end, a diameter of the second end being larger than a diameter of the first end.
6 . The capillary bonding tool of claim 5 , wherein the diameter of the first end of the second opening is generally equal to a diameter of the first opening.
7 . The capillary bonding tool of claim 5 , wherein the diameter of the second end of the second opening is generally equal to a diameter of the third opening.
8 . The capillary bonding tool of claim 1 , wherein a diameter of the third opening is essentially constant along the central longitudinal axis.
9 . The capillary bonding tool of claim 1 , wherein the first opening has a cylindrical shape.
10 . The capillary bonding tool of claim 1 , wherein the second tapered opening is in the form of a chamfer.
11 . The capillary bonding tool of claim 1 , wherein the third opening has a cylindrical shape.
12 . A method of making a ball bond, the method comprising:
passing a bond wire through a wire bonding system, the wire bonding system having a bonding capillary, the bonding capillary having a body and a peripheral ridge axially extending outwardly from the body, the peripheral ridge having a distal end surface and a ball containment recess formed in the distal end surface;
forming a ball by heating a first end of the bond wire positioned in the ball containment recess, such that the formed ball is fully contained within the ball containment recess; and
bonding the formed ball to an electrical contact.
13 . The method of claim 12 , wherein the distal end face of the peripheral ridge is a bonding surface.
14 . The method of claim 12 , wherein the ball containment recess has a cylindrical shape.
15 . The method of claim 12 , wherein the peripheral ridge extends generally perpendicularly away from the body toward the electrical contact.